People, culture, and alignment with the original transaction thesis. Everything should be compared to that transaction thesis. Failure to align decisions with the transaction thesis will ultimately lead to a failed transaction. People are the most important asset for the business, especially for a small (headcount) startup in the tech space. If you fail to retain the right talent during the integration, or they leave within the first 1 – 3 years post-merger, then you loose the intellectual capability they possess and the creative driver that led to the merger in the first place. Some of that talent can be replaced, after all, we are all replaceable, but not all can be and definitely not the unique ideas that key players possess. In a small startup, that can be devastating whether a tech company or some other industry.